1. Field of Invention
The invention generally relates to compositions for protecting textiles from light and soil, and in particular, for inhibiting or preventing color fade and related damage from sunlight. The invention also relates to methods of use for the compositions.
2. Description of Related Art
Textiles comprise a multitude of fibers. The fibers are generally of two types: (1) natural fibers, such as protein fibers (wool, silk) from animals or cellulosic fibers (cotton) from plants; and (2) synthetic fibers, such as nylon, polyester, olefin, and acrylic fibers, that are man-made from thermoplastic materials. While these individual fibers have certain beneficial properties, they also suffer from various weaknesses. For example, wool has good absorbence allowing for good reactivity with dyes, but wool also stains very easily and is difficult to clean. Cellulosic fibers, such as cotton and rayon (a reformulated form of cotton and wood pulp), are susceptible to the effects of light, and particularly sunlight, which causes loss of color intensity on the fiber. Linen, a natural fiber derived from flax, loses strength and color when exposed to sunlight.
While synthetic fibers are popular, inexpensive, heat resistant, and durable, in general, they too have certain deficiencies. For example, polyester is susceptible to oil stains. Olefinic fibers are not resilient and are crushed under constant weight. Synthetic fibers, in general, are also susceptible to light, and fade or discolor upon exposure thereto. Thus, there is a need to protect fibers from the damaging effects of light, particularly sunlight, and from contact with stain-producing substances and physical stress.
Many textile materials experience sun fade. “Sun fade” is generally defined as “the gradual, irreversible loss of color intensity due to exposure to sunlight.” Sun fade is more common in areas of high solar intensity, such as in the sunbelt states in the U.S. and tropical and subtropical climates, than in colder climates. Sun fade occurs on fibers which are exposed to direct sunlight, and generally does not appear on fibers located in shaded areas, such as behind or under furniture, or inside rooms receiving no sunlight.
The ultra-violet (UV) and visible regions of light are responsible for color fading on textiles. More specifically, light in the near UV region of 315 nm–400 nm (also known as UV-A) contributes more to fading than light in the region of 280 nm–315 nm (also known as UV-B), which in turn contributes more to fading than light in the far UV region of 100 nm–280 nm (also known as UV-C). Visible light (380 nm–770 nm) also contributes to color fade and is thought to contribute more to light fading than UV-A. For example, visible light-induced oxidation of dyes on fibers generally causes the color intensity to fade. Thus, there is a need to protect fibers from the color-fading effects of UV and visible light.
The textile industry has proposed a number of ways to address the problem of color fading and, particularly, the loss of dye color intensity of a textile from light. For example, an experienced dye technician may simply re-dye the faded fabric in an effort to restore the color. However, this method of correction is dependent upon fiber type. Unlike fibers such as nylon and wool, some fibers generally do not dye well on-site. In addition, this method is quite expensive, and it is often difficult to accurately match non-re-dyed areas of the fabric. As an alternative to re-dyeing, direct sunlight can be blocked with draperies or shades, or by applying UV-blocking films to windows. Generally, these measures are not desirable because they reduce the overall lighting of the room.
More recently, compounds, generally characterized as UV absorbers, UV blockers, UV inhibitors, light stabilizers, light inhibitors, antioxidants, and the like, have been developed to reduce or prevent the fading of colors and deterioration of textiles caused by light. UV absorbing agents such as para-aminobenzoic acid (PABA) have been used for nearly half a century as UV screening agents. U.S. Pat. No. 4,153,744 teaches the use of a tetrakis (hydroxymethyl) phosphonium salt to impart resistance to UV light-induced color change in vat-dyed cellulosic textile materials. Similarly, U.S. Pat. No. 4,788,054 teaches the use of N-phenylphthalisoimides as ultraviolet radiation absorbers for cotton, wool, polyester, and rayon fabrics.
Foreign matter, either solids or liquids, and generally referred to as “soil”, that contacts a textile also causes damage to the textile. The damage may be costly, generally requiring repair of the damaged area, and may even require replacement of the entire textile. Poly(ethylene terephthalate)/poly(ethylene glycol) has been shown to absorb onto hydrophobic surfaces of textile fibers, thereby conferring soil-release properties to such textiles.
However, there is a need for improved methods and compositions for use with textile materials.